CC BY
9
Obidov Abdulxay,
associate professor, department of Agricultural Machines Tashkent Institute of Irrigation and Mechanization Enjeneers,
Republic of Uzbekistan Xoliyarov Yormamat Berdiqulovich, candidate, of technical sciences, Senior Researcher, Soil Processing Department, Scientific Research Institute of Mechanization and Electrification of Agriculture (SRIMEA), Tashkent Mamatov Farmon Murtozevich, professor, Head of the Department of scientific-applied researches and Innovation Karshi Engineering-Economics Institute,
(Republic of Uzbekistan), E-mail: [email protected]
MODELING OF INDICATORS OF CULTIVATOR CHEESE WORK
Abstract: The technique for planning an experiment using the theory of similarity and uniformity in operational studies of agricultural aggregates is considered. The results of experimental studies with an aggregate for presowing soil cultivation are presented.
Keywords: modeling, chisel-cultivator, experiment planning, soil cultivation, preseeding aggregate.
Introduction. One of the features of the use of agricultural machinery is the extreme variety of conditions of its work [1]. In this regard, in order to ensure the highest efficiency of the use of aggregates, the optimization of parameters and their operating modes should be carried out not only taking into account the possible range of variation of these conditions, but also in relation to specified conditions. The solution to this problem is complicated by the fact that the existing methods of obtaining information on the performance of aggregates do not allow us to generalize it in terms of working conditions, reflecting the effects on these indicators. However, without such a generalization, the results of the experiment are always of a private nature, reflecting the conditions for conducting it.
In this connection, the derivation of dependencies describing the relationship between the i-th performance indicator of a machine or an aggregate on the operating factors characterizing the conditions is an independent task.
The discussion of the results. Let's consider a technique of modeling of indicators of work of agricultural machines on an example of a chisel-cultivator. Its main performance indicators are the tractive resistance R and the depth of travel ap. The operating conditions of this machine are uniquely determined by the installation depth a, the speed of movement of the aggregate V and the soil state, for its quantitative evaluation, its density p (g/cm3) and hardness H (mPa) can be used [2].
The dependence of R and ap on the factors determining the working conditions of the chisel-cultivator can be generally represented as
R = fMp;B;V;p;H;g); ap = f2(ay;B;V;p;H;g), (l)
where B - is the design width of the machine, m; g - is the acceleration due to gravity, m/sec2.
The value of g is included in the dependence (l) in accordance with the requirements of the theory of dimensions [3]. Using as the basis variables the factors B, H and g, whose dimensional matrix is different from zero, we represent the relations (l) in the form
R , ae V pgB, ap , a V pgB
HB2
■=tA ; PgB); ^ = ^ , ,
1 B VgB; H B B VgB; H
-). (2)
Such a transformation of response functions into a dimen-sionless form leads to a reduction in the number of variables and greatly facilitates the scope of work in determining the required dependencies.
As the results of numerous studies show, for the soil-cultivating machines the dependences R = f(a) and ap = f(ap; V) are linear, R = f(V) - parabolic, but can be linearized by replacing V by V2. In the transition to the dimensionless form of the considered dependences (2), the nature of these relationships is preserved, since factors B = const and g = const.
Taking into account the nature ofthe dependence R = f(V), on the basis of the corollary of the ^-theorem [2, 3], we transform relation (2) to the form
MODELING OF INDICATORS OF CULTIVATOR CHEESE WORK
HB2 ^ B ' gB ' H )
(3)
Its use opens up new possibilities for improving the experimental procedure in those cases when, for whatever reason, information about the magnitude of a is not required ap.
Taking into account the comments on the structure of the particular dependences of relations (2) and (3), they can be approximated by a polynomial of the first order [4]
y = bo +^Lbixix, + - (4)
where bo and b. - are regression coefficients; xi are independently factors in coded form.
This model allows to take into account both the linear effect of each of the factors, and the result of their interaction.
During the experiment, the sequence of experiments is established using a table of random numbers. All experiments are carried out only at two fixed levels of factor values. This requirement is easily implemented for factors (a/B) and (pgB/H). The predetermined level of factors V / yfgB or V2/gB and (ap/B) is practically impossible to sustain, since, for example, the value of V for the aggregate depends on the traction resistance of the machine. However, this dif-
22
cm
20
18
aP 16
14
12
1
2.
VI
ficulty is easily eliminated. On the basis of experimental data, using the static methods, we can find the equations of the dependences ap = f(V) and R = f(ap, V2) for each soil conditions and the installation depth. From these equations, the values of R and ap are calculated with the required combination of factor levels: V2 / JgB ; (a/B); V / JgB . In this case, fixed levels are chosen within the range of their actual values variation with appropriate combinations of values of other factors. To test the hypothesis of the adequacy of the representation of the results by the polynomial (4), the Fisher criterion (F-test) is used [4, 5].
Experimental research of the unit (T-4A tractor and Chekul-cultivator CHKU-4) for soil fertilization was carried out in farms of Uzbekistan.
Analysis of experimental studies shows that the function Rx = f(ap) is linear, but the influence of the depth of the stroke on the value of R for all soil conditions increases with the
x
speed of movement of the aggregate.
It can be seen from (Fig. 1) that the rate of change in the value of the complex R/HBK2 from the jgB/H, factor, which characterizes the soil conditions, essentially depends on the operating mode of the aggregate.
10
1
2
0 13 16 19 cm 22
14
20
26
6,9
6,2
5,5
4,8
4,3
3,7
3,1
2,5
Figure 1. Graphs of the ap; R/HB2; R/HBk2 u a/Bkfor the CHKU-4 chisel-cultivator: 1 -for V = 1.89 m/s and a = 22 cm; 2 - at V = 1,89 m/s and a = 10 cm; - R ; - a
Analysis of the information obtained with these models (fig. 1) shows that the influence of the depth ap of the aperture on the value of R increases with the increase in the speed of motion of the MTA for all soil conditions. The influence of the speed of motion, estimated from the value of the coefficient for the term V2 in the dependence R = f(V2) also depends on the value of other factors.
A similar picture holds for the factor (pgB/H) in the dependence R/HB2 = f(pgB/H).
The obtained mathematical models of performance indicators of the chisel-cultivator will allow to study in detail the influence of any of the factors on the magnitude of its traction resistance and the depth of the stroke. They can be used for operational calculations to justify the optimal composition and operating conditions of the chisel-cultivator unit under given conditions.
The conclusion. The application of methods of the theory of similarity and experiment planning in the testing of chiesel aggregates significantly increase the amount of
information obtained about the operational properties of the of resistance and depth of a course of a chisel-cultivator at unit. The received mathematical models allow to define values work of the unit in any given operational conditions.
References:
1. Mamatov F. M., Batirov Z. L., Xalilov M. S. Chisel-cultivator-fertilizer for forming ridges and applying fertilizers // Vena: European science review.- No. 3-4.- 2018.- P. 267-269.
2. Шаров Н. М. Показатели оценки почвенных условий // Механизация и электрификация социалистического сельского хозяйства.- № 2.- 1975.- C. 26-29.
3. Седов Л. И. Методы подобия размерности в механика.- Москва: Наука.- 1997.
4. Мельников С. В., Алешин В. Р., Рощин Н. М. Планирование эксперимента в исследованиях сельскохозяйственных процессов.- Ленинград: Колос.- 1972.
5. Саклаков В. Д. Технико-экономическое обоснование выбора средств механизации.- Москва: Колос.- 1993.
